— From Alan Jardine.
You can add Design to your toolbar or list of bookmarks in a second, then with any web page loaded use it to take measurements directly from the page with absolute accuracy.
One niggle, though. The lack of IE6 support means it can’t be used to help fix the inevitable layout bugs encountered when developing for that browser. But I suspect IE6’s bugginess would make porting Design a nightmare, so it’s a forgiveable omission.